Wastewater Monitoring During COVID-19 Epidemic: the Experience in the Veneto Region (Italy) (Preprint)

BACKGROUND As the COVID-19 pandemic has affected populations around the world, researchers are turning to wastewater-based epidemiology (WBE) testing as a potential tool to monitor the spread of the virus. SARS-CoV-2 concentrations in wastewater are thought of possibly anticipating COVID-19 epidemic curve. OBJECTIVE The study aims to examine this association and its potential use in tracking pandemic trends. METHODS The temporal series of COVID-19 confirmed cases was compared with SARS-CoV-2 RNA concentration in wastewater (in terms of genomic copies/µL) between 05/10/2021 and 14/02/2022 in the Veneto Region, NE Italy. Data from regional databases for confirmed cases, hospitalizations, and intensive care units (ICU) admissions were used. Cumulative sum (CUSUM) charts were used to compare the temporal series. RESULTS The study found that an increase of viral load in wastewater samples from December 2021 to January 2022 was followed by an increase in positive cases of COVID-19 with a 5-day delay. SARS-CoV-2 RNA peaks in wastewater anticipated positive case peaks by an average of 5.2 days. The study also found a 4.25-day average time between detecting notable values in wastewater and hospitalizations, with certain healthcare districts exhibiting stronger correlations than others. The study observed limited correlations between wastewater and ICU admissions. However, certain healthcare districts exhibited stronger correlations, with notable values in wastewater anticipating ICU admissions by an average of 13.5 and 9.5 days for two specific districts. CONCLUSIONS Wastewater testing can provide valuable insights into the level of COVID-19 in a community, including asymptomatic cases, thus providing a precious early-warning tool for infectious disease outbreaks with pandemic potential.